"It is a possibility that the authorization is approved under conditions (...) but we are at a very early stage, the transaction has just been proposed, we have to analyse it and the government has to decide," Sebastian Albella, chairman of Spain's regulator CNMV said on Monday.

Albella did not explain what conditions he was referring to.

Pan-European stock market operator Euronext and Switzerland's SIX sparked a bidding war for Spain’s Bolsas y Mercados Espanoles (BME) BME.MC on Monday, with both trying to snap up one of Europe’s last standalone stock exchanges.

(Reporting By Jesús Aguado; editing by Elena Rodriguez)